To separate the phosphorus-containing phase from steel slag,the effects of B_(2)O_(3)and Na_(2)B_(4)O_(7)on the enrichment of phosphorus-containing phases in Ca_(2)SiO_(4)–Ca_(3)(PO_(4))_(2)(C_(2)S–C_(3)P)solid solu...To separate the phosphorus-containing phase from steel slag,the effects of B_(2)O_(3)and Na_(2)B_(4)O_(7)on the enrichment of phosphorus-containing phases in Ca_(2)SiO_(4)–Ca_(3)(PO_(4))_(2)(C_(2)S–C_(3)P)solid solution were comparatively analyzed through theoretical calculations and experimental investigations.The results indicate that the optimum reaction temperature between B_(2)O_(3)and C_(2)S–C_(3)P is 800℃.The phase compositions of C_(2)S–C_(3)P equilibrium system with 5 wt.%B_(2)O_(3)at 800℃ included Ca_(3)(PO_(4))_(2),CaSiO_(3)and Ca11B_(2)Si_(4)O_(22),among which the content of Ca_(3)(PO_(4))_(2)was the highest.For C_(2)S–C_(3)P with 5 wt.%Na_(2)B_(4)O_(7)equilibrium system,Ca_(3)(PO_(4))_(2),CaSiO_(3),Ca11B_(2)Si_(4)O_(22)and Na_(2)Ca_(2)P_(2)O_(8)were independent at 390–690℃.Ca_(3)(PO_(4))_(2)and Ca_(2)SiO_(4)precipitated in the solid solution when the addition of B_(2)O_(3)was more than 6 wt.%,and the content of Ca_(3)(PO_(4))_(2)raised with the increase in the addition of B_(2)O_(3).The main phases in the C_(2)S–C_(3)P solid solution with Na_(2)B_(4)O_(7)were(Ca_(2)SiO_(4))0.05[Ca_(3)(PO_(4))_(2)],Ca_(2)SiO_(4)and Na_(3)Ca_(6)(PO_(4))_(5)at 650℃.And when the addition of Na_(2)B_(4)O_(7)exceeded 6 wt.%,the content of Na_(3)Ca_(6)(PO_(4))_(5)increased significantly.There was no precipitation of Ca_(3)(PO_(4))_(2)or boron-containing phase in the samples with Na_(2)B_(4)O_(7),but a small proportion of Ca_(3)(PO_(4))_(2)transformed into(Ca_(2)SiO_(4))0.05[Ca_(3)(PO_(4))_(2)],and Ca^(2+)was partially replaced by Na^(+)to generate Na_(3)Ca_(6)(PO_(4))_(5).As a result,the temperature for Na_(2)B_(4)O_(7)to enrich the phosphorus-containing phase in C_(2)S–C_(3)P solid solution was lower than that for B_(2)O_(3).However,the grade of the phosphorus-containing phase for Na_(2)B_(4)O_(7)was lower than that for B_(2)O_(3).展开更多
The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permangan...The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permanganate as a surface treatment. The surface-modified manganese sand was found to be most efficient at removing iron and manganese from water. The metal concentrations in filtered effluent were between 0.01 and 0.04 mg/L, which is far lower than the standard for recycle water. A concen-tration of 5% KMnO4 was found to be most effective as surface modifier. The surface of the manganese sand modified by 5% KMnO4 was examined and found to be covered with a dense membrane of some compound. The membrane had the advantages of uniform texture, large surface area and physical and chemical stability. It was effective at removing iron and manganese from mine water.展开更多
Density, pH, viscosity, conductivity and the Raman spectra of aqueous NaB（OH）4 solutions precisely measured as functions of concentration at different temperatures （293.15, 298.15, 303.15, 313.15 and 323.15 K） are...Density, pH, viscosity, conductivity and the Raman spectra of aqueous NaB（OH）4 solutions precisely measured as functions of concentration at different temperatures （293.15, 298.15, 303.15, 313.15 and 323.15 K） are presented. Polyborate distributions in aqueous NaB（OH）4 solution were calculated, covering all the concentration range, B（OH）4 is the most dominant species, other polyborate anions are less than 5.0%. The volumetric and the transport properties were discussed in detail, both of these properties indicate that B（OH）4 behaves as a struc- ture-disordered anion.展开更多
In order to obtain better carbonation effect, extraction behavior of slag batch is necessary to study. Relevant parameters like selective extraction yield were originally discussed. The relationship between selective ...In order to obtain better carbonation effect, extraction behavior of slag batch is necessary to study. Relevant parameters like selective extraction yield were originally discussed. The relationship between selective extraction yield and conversion ratio was systemically focused on. The results show that alkaline earth metal conversion ratio is changed with leaching time and NH4CI concentration by first order exponential, and the maximum conversion for calcium keeps about 68% at 120 min in 0.4 mol/L NH4C1 solution, while leaching temperature and particle size have a linear effect on conversion ratio. Selective extraction yield of calcium is more than 93%, and the value of Mg is less than 5%. Apparent layer bands of silicon and calcium appear in the surface area through morphology detection of slag after leaching, and the case for 38-75 μm slag batch is more obvious than 75 150 μm slag and slag with larger particle size when leaching in 0.4 mol/L NH4Cl solution for 90 rain at 60 ℃.展开更多
The TiO 2 nanotube sample was prepared via a NaOH solution in a Teflon vessel at 150℃. The as-prepared nanotubes were then treated with H 2SO 4 solutions. The TiO 2 nanotube has a crystalline structure with open-...The TiO 2 nanotube sample was prepared via a NaOH solution in a Teflon vessel at 150℃. The as-prepared nanotubes were then treated with H 2SO 4 solutions. The TiO 2 nanotube has a crystalline structure with open-ended and multiwall morphologies. The TiO 2 nanotubes before and after surface acid treatment were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and UV-VIS dispersive energy spectrophotometry(DRS). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of acid orange II in aqueous solutions. It was found that the order of photocatalytic activity was as follows: TiO 2 nanotubes treated with 1.0 mol/L H 2SO 4 solution (TiO 2(1.0M H 2SO 4) nanotubes)>TiO 2 nanotubes treated with 0.2 mol/L H 2SO 4 solution (TiO 2(0.2M H 2SO 4) nanotubes)>TiO 2 nanotubes >TiO 2 powder. This was attributed to the fact that TiO 2 nanotubes treated with H 2SO 4 was composed of smaller particles and had higher specific surface areas. Furthermore, the smaller TiO 2 particles were beneficial to the transfer and separation of photo-generated electrons and holes in the inner of and on the surface of TiO 2 particles and reduced the recombination of photo-generated electrons and holes. Acid treatment was particularly effective for TiO 2 nanotubes, this increase in activity was correlated with the concentration of H 2SO 4 solution.展开更多
Silica sol ceramic mold was made at room temperature with JN-30 silica sol, silica powder and NH4Cl. It is found that the harden time of silica sol ceramic mold is only 0.5 to 1.5 h under the amount of NH4Cl solution ...Silica sol ceramic mold was made at room temperature with JN-30 silica sol, silica powder and NH4Cl. It is found that the harden time of silica sol ceramic mold is only 0.5 to 1.5 h under the amount of NH4Cl solution of 7% to 8% with 15% concentration, and less surface cracks occur by using vacuum drying. The proper vacuum drying process parameters： vacuum drying temperature is 80 to 100℃, drying time is 5 h and vacuum is 0.06 to 0.07MPa. The harden mechanics, vacuum drying mechanics and the reason of less surface cracks of silica sol ceramic mold by vacuum drying： were also analyzed in this paper.展开更多
The GC determination of aldehydes and ketones in stack gas was reported. The stack gas was collected with the dust sampler by isokinetic sampling technique, 2,4 dinitrophenylhydrazine in acidic solution was used to a...The GC determination of aldehydes and ketones in stack gas was reported. The stack gas was collected with the dust sampler by isokinetic sampling technique, 2,4 dinitrophenylhydrazine in acidic solution was used to absorb aldehydes and ketones in stack gas specifically, to form their hydrazones, which were determined by GC with a capillary column of SE 54. The GC system can separate nine hydrazones of carbonyls interested with constant recovery rates of 94%—97%, giving lowest detectable limits of 0 05—1 0 ng. The standard gas of carbonyls were determined by this method with relative errors of -5% to -10%, percent coefficients of variation within 5%, and spiking recovery rates of 93%—97%. As an application of the method, the carbonyl pollutants were determined in stack gas samples of a chemical plant.展开更多
By means of ^（29）Si and ^（27）Al magic angle spinning nuclear magnetic resonance（MAS NMR） combined with deconvolution technique, X-ray diffraction（XRD）, scanning electron microscopy（SEM） as well as energy dis...By means of ^（29）Si and ^（27）Al magic angle spinning nuclear magnetic resonance（MAS NMR） combined with deconvolution technique, X-ray diffraction（XRD）, scanning electron microscopy（SEM） as well as energy dispersive X-ray system（EDX）, the effect of 5 wt% corrosive solutions（ viz. 5 wt% Na_2SO_4, MgSO_4, Na_2SO_^（4＋）Na Cl and Na_2SO_^（4＋）Na Cl＋Na_2CO_3） on C-S-H microstructure in portland cement containing 30 wt% fly ash was investigated.The results show that, in MgSO_4 solution, Mg2＋ promotes the decalcification of C-S-H by SO_4^（2-）,increasing silicate tetrahedra polymerization and mean chain length（MCL） of C-S-H. However, the substituting degree of Al^（3＋） for Si^（4＋）（Al[4]/Si） in the paste does not change evidently. Effect of Na_2SO_4 solution on C-S-H is not significantly influenced by Na Cl solution, while the MCL and Al[4]/Si of C-S-H in fly ashcement paste slightly change. However, the decalcification of C-S-H by SO_4^（2-） and CO_3^（2-） attack, as well as the activation of fly ash by SO_4^（2-） attack will increase the MCL and Al[4]/Si, which are both higher than that under Na_2SO_4 corrosion, MgSO_4 or Na_2SO_4 ＋Na Cl coordination corrosion.展开更多
The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance ...The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy,and X-ray photoelectron spectroscopy.The experimental results show that the optimal parameters for KAl(SO_(4))_(2)sealing are 35℃,with the pH value of 8,the concentration of 8 g/L,and the sealing time of 3 min.The corrosion resistance of the KAl(SO_(4))_(2)sealed sample can be significantly improved than that of unsealed one,and is obviously superior to that of the conventional hydrothermal sealed sample.Furthermore,X-ray photoelectron spectroscopy demonstrates that more Al(OH)_(3)will be formed in the process of KAl(SO_(4))_(2)sealing,which will shrink the diameter of the microporous and therefore results in the excellent corrosion resistance.展开更多
The synthesis of Cu-doped ZnO nanosheets at room temperature was reported in our previous paper. The effects of annealing temperature on Cu-doped ZnO nanosheets were studied in this paper. Cu-doped ZnO nanosheets were...The synthesis of Cu-doped ZnO nanosheets at room temperature was reported in our previous paper. The effects of annealing temperature on Cu-doped ZnO nanosheets were studied in this paper. Cu-doped ZnO nanosheets were annealed at 200-500℃ in air. The annealed specimens were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The results show that Cu concentration in Cu-doped ZnO nanosheets reduced with increasing annealing temperature. When annealing temperature was lower than Zn melting point （410℃）, the morphologies of the Cu-doped ZnO nanosheets remained nearly the same as that before annealing. However, when the annealing temperature was over Zn melting point, Cu-doped ZnO nanosheets changed to nanowires, wormlike nanosheets or did not change. The change of Cu concentration in Cu-doped ZnO nanosheets is explained by oxidation thermodynamics. A physical model is suggested to explain the morphology changes of Cu-doped ZnO nanosheets, based on the existence of Cu-rich layer beneath Cu-doped ZnO nanosheets.展开更多
A regenerative absorption process for removal of SOx from FCC off-gas using LAS/ H2SO4 solution as absorbant was studied and pilot-plant experiments were carried out. A mass transfer- reaction model for the SO2 absorp...A regenerative absorption process for removal of SOx from FCC off-gas using LAS/ H2SO4 solution as absorbant was studied and pilot-plant experiments were carried out. A mass transfer- reaction model for the SO2 absorption process was established based on pilot-plant experiments, and the concentration distribution of components in the liquid film, and the partial pressure and mass transfer rate of SO2 along the height of the absorption tower, was calculated from this model. The numerical simulation results were compared with the experimental results and proved that the model can be used for describing the SO2 absorption process.展开更多
Under the framework of white noise analysis, the existence of scattering solutions to the abstract dynamical φ4^4 wave equations in terms of generalized operators （see Section 3 below） is proven via a combination o...Under the framework of white noise analysis, the existence of scattering solutions to the abstract dynamical φ4^4 wave equations in terms of generalized operators （see Section 3 below） is proven via a combination of the characterization for the symbol of generalized operators and the classical scattering results. In addition, some properties （Poincare invariance and irreducibility） of the solutions are discussed.展开更多
Time-resolved IR absorption spectroscopy has been used to atudy the photochemistry of W(CO)_6 in cyclohexane, carbon tetrachloride, and the mixture of carbon tetrachloride and cyelohexane. The reastion of photolytical...Time-resolved IR absorption spectroscopy has been used to atudy the photochemistry of W(CO)_6 in cyclohexane, carbon tetrachloride, and the mixture of carbon tetrachloride and cyelohexane. The reastion of photolytically generated W(CO)_5. C_6H_(12) with CCl_4 was investigated. An intermediate with a lifetime of about 0.5ms, presumably attributed as W(GO)_5.CCl_4, was first observed.展开更多
In this study,the benign target double terpyridine parts based amphiphilic ionic molecules(AIMs 1,2)and the reference single terpyridine segment included AIMs(AIMs 3,4)were synthesized through a multi-step method,and ...In this study,the benign target double terpyridine parts based amphiphilic ionic molecules(AIMs 1,2)and the reference single terpyridine segment included AIMs(AIMs 3,4)were synthesized through a multi-step method,and the molecular structures were fully characterized.The excellent anticorrosion of the target AIMs for copper surface in H_(2)SO_(4) solution was demonstrated by the electrochemistry analysis,which was more superior over those of the reference AIMs.The standard adsorption free energy changes of the target AIMs calculated by the adsorption isotherms were lower than -40 kJ·mol^(-1),suggesting an intensified chemical adsorption on metal surface.The molecular modeling and molecular dynamic computation of the studied AIMs were performed,demonstrating that the target AIMs exhibited lower highest occupied molecular orbital-lowest unoccupied molecular orbital energy gaps and greater adsorption energies than the reference ones.The chemical adsorption of the AIMs on metal surface was revealed by various spectroscopic methods including scanning electron microscopy,atomic force microscopy,Fourier transform infrared spectroscopy,attenuated total reflection infrared spectroscopy,Raman and X-ray diffraction.展开更多
The cyclic plastic straining electrode technique has been used to investigate the transient electrochemical behaviour of Fe-26Cr1Mo stainless steel in 1M H2SO4 solution at a passive potential.The influence of plastic ...The cyclic plastic straining electrode technique has been used to investigate the transient electrochemical behaviour of Fe-26Cr1Mo stainless steel in 1M H2SO4 solution at a passive potential.The influence of plastic strain amplitude and plastic strain rate on the dissolution current response was analysed. The experimental results showed that the transient current was dependent on the competitive process of the surface film rupture and repassivation of the new surface. The high plastic strain amplitude and the high plastic strain rate caused a change of electrochemical activity of specimen surface. In the condition of low strain amplitude and strain rate, the characteristics of current response was mainly relative tp the process of new surface repassivation.The competition kinetics has been analysed through the comparison of plastic strain rate and repassivating rate展开更多
Oil and gas line pipes are laid underground and run through different areas in the laying process,so they will be subjected to different degrees of corrosion and even crack,leading to enormous casualties and economic ...Oil and gas line pipes are laid underground and run through different areas in the laying process,so they will be subjected to different degrees of corrosion and even crack,leading to enormous casualties and economic losses.In order to guarantee the safe operation of line pipes,therefore,it is significant to investigate the electrochemical corrosion behaviors of pipe steel in a simulated soil environment.In this paper,the electrochemical corrosion behaviors of the base metals and welding materials of API 5L X90 steel longitudinally submerged arc welding pipes in near-neutral simulated soil solution(NS4)were studied by means of the electrochemical impedance spectroscopy(EIS)and the potentiodynamic polarization testing technology.It is shown that the typical characteristic of anodic dissolution is presented but with no passivation phenomenon when X90 linepipe steel is put in NS4 solution.The base material is thermodynamically more stable than the seam weld material.The base material and seam weld samples were polarized under -850 mV polarization potential for different durations.It is demonstrated that with the proceeding of polarization,the polarization resistance and the corrosion resistance increase while the corrosion current density decreases.And the corrosion resistance of base material is better than that of seam weld material.展开更多
A surface E is a graph in R^4 if there is a unit constant 2-form ω on R^4 such that <e_1∧e_2.ω>≥v_0>0 where{e_1.e_2}is an orthonormal frame on Σ.We prove that.if v_0≥on the initial snrface,then the mean...A surface E is a graph in R^4 if there is a unit constant 2-form ω on R^4 such that <e_1∧e_2.ω>≥v_0>0 where{e_1.e_2}is an orthonormal frame on Σ.We prove that.if v_0≥on the initial snrface,then the mean curvature flow has a global solution and the scaled surfaces converge to a self-similar solution.A surface Σ is a graph in M_1×M_2 where M_1 and M_2 are Riemann surfaces. if<e_1∧e_2.ω>≥v_0>0 where w_1 is a Khler form on M_1.We prove that.if M is a Khler-Einstein surface with scalar curvature R.v_0≥ on the initial surface,then the mean curvature flow has a global solution and it sub-converges to a minimal surface,if.in addition.R≥0 it converges to a totally geodesic surface which is holomorphic.展开更多
基金funding support from the National Key R&D Program of China(2020YFC1909105)the 2023 Basic Research Foundation Project for Universities in the Inner Mongolia Autonomous Region(2023RCTD006)+1 种基金the Major Science and Technology Project of Inner Mongolia Autonomous Region(2021ZD0016)the National Natural Science Foundation of China(51664044).
文摘To separate the phosphorus-containing phase from steel slag,the effects of B_(2)O_(3)and Na_(2)B_(4)O_(7)on the enrichment of phosphorus-containing phases in Ca_(2)SiO_(4)–Ca_(3)(PO_(4))_(2)(C_(2)S–C_(3)P)solid solution were comparatively analyzed through theoretical calculations and experimental investigations.The results indicate that the optimum reaction temperature between B_(2)O_(3)and C_(2)S–C_(3)P is 800℃.The phase compositions of C_(2)S–C_(3)P equilibrium system with 5 wt.%B_(2)O_(3)at 800℃ included Ca_(3)(PO_(4))_(2),CaSiO_(3)and Ca11B_(2)Si_(4)O_(22),among which the content of Ca_(3)(PO_(4))_(2)was the highest.For C_(2)S–C_(3)P with 5 wt.%Na_(2)B_(4)O_(7)equilibrium system,Ca_(3)(PO_(4))_(2),CaSiO_(3),Ca11B_(2)Si_(4)O_(22)and Na_(2)Ca_(2)P_(2)O_(8)were independent at 390–690℃.Ca_(3)(PO_(4))_(2)and Ca_(2)SiO_(4)precipitated in the solid solution when the addition of B_(2)O_(3)was more than 6 wt.%,and the content of Ca_(3)(PO_(4))_(2)raised with the increase in the addition of B_(2)O_(3).The main phases in the C_(2)S–C_(3)P solid solution with Na_(2)B_(4)O_(7)were(Ca_(2)SiO_(4))0.05[Ca_(3)(PO_(4))_(2)],Ca_(2)SiO_(4)and Na_(3)Ca_(6)(PO_(4))_(5)at 650℃.And when the addition of Na_(2)B_(4)O_(7)exceeded 6 wt.%,the content of Na_(3)Ca_(6)(PO_(4))_(5)increased significantly.There was no precipitation of Ca_(3)(PO_(4))_(2)or boron-containing phase in the samples with Na_(2)B_(4)O_(7),but a small proportion of Ca_(3)(PO_(4))_(2)transformed into(Ca_(2)SiO_(4))0.05[Ca_(3)(PO_(4))_(2)],and Ca^(2+)was partially replaced by Na^(+)to generate Na_(3)Ca_(6)(PO_(4))_(5).As a result,the temperature for Na_(2)B_(4)O_(7)to enrich the phosphorus-containing phase in C_(2)S–C_(3)P solid solution was lower than that for B_(2)O_(3).However,the grade of the phosphorus-containing phase for Na_(2)B_(4)O_(7)was lower than that for B_(2)O_(3).
基金provided by the National Hi-tech Research and Development Program of China (No.2008AA06z305)the National Natural Science Foundation of China (No.50678172)the Science and Technology Research Program of the Ministry of Education of China (No.107022)
文摘The iron and manganese absorption properties of several filter media were studied. Four plain filter media and six surface-modified media were examined. The surface modification was performed using potassium permanganate as a surface treatment. The surface-modified manganese sand was found to be most efficient at removing iron and manganese from water. The metal concentrations in filtered effluent were between 0.01 and 0.04 mg/L, which is far lower than the standard for recycle water. A concen-tration of 5% KMnO4 was found to be most effective as surface modifier. The surface of the manganese sand modified by 5% KMnO4 was examined and found to be covered with a dense membrane of some compound. The membrane had the advantages of uniform texture, large surface area and physical and chemical stability. It was effective at removing iron and manganese from mine water.
基金Supported by the National Natural Science Foundation of China （20873172） and Main Direction Program of Knowledge In- novation of Chinese Academy of Sciences （KZCX2-EW-307）.
文摘Density, pH, viscosity, conductivity and the Raman spectra of aqueous NaB（OH）4 solutions precisely measured as functions of concentration at different temperatures （293.15, 298.15, 303.15, 313.15 and 323.15 K） are presented. Polyborate distributions in aqueous NaB（OH）4 solution were calculated, covering all the concentration range, B（OH）4 is the most dominant species, other polyborate anions are less than 5.0%. The volumetric and the transport properties were discussed in detail, both of these properties indicate that B（OH）4 behaves as a struc- ture-disordered anion.
基金Project(2006BAE03A07)supported by National Key Technology Research and Development Program of 11th Five-year Plan of China
文摘In order to obtain better carbonation effect, extraction behavior of slag batch is necessary to study. Relevant parameters like selective extraction yield were originally discussed. The relationship between selective extraction yield and conversion ratio was systemically focused on. The results show that alkaline earth metal conversion ratio is changed with leaching time and NH4CI concentration by first order exponential, and the maximum conversion for calcium keeps about 68% at 120 min in 0.4 mol/L NH4C1 solution, while leaching temperature and particle size have a linear effect on conversion ratio. Selective extraction yield of calcium is more than 93%, and the value of Mg is less than 5%. Apparent layer bands of silicon and calcium appear in the surface area through morphology detection of slag after leaching, and the case for 38-75 μm slag batch is more obvious than 75 150 μm slag and slag with larger particle size when leaching in 0.4 mol/L NH4Cl solution for 90 rain at 60 ℃.
文摘The TiO 2 nanotube sample was prepared via a NaOH solution in a Teflon vessel at 150℃. The as-prepared nanotubes were then treated with H 2SO 4 solutions. The TiO 2 nanotube has a crystalline structure with open-ended and multiwall morphologies. The TiO 2 nanotubes before and after surface acid treatment were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and UV-VIS dispersive energy spectrophotometry(DRS). The photocatalytic activity of the samples was evaluated by photocatalytic degradation of acid orange II in aqueous solutions. It was found that the order of photocatalytic activity was as follows: TiO 2 nanotubes treated with 1.0 mol/L H 2SO 4 solution (TiO 2(1.0M H 2SO 4) nanotubes)>TiO 2 nanotubes treated with 0.2 mol/L H 2SO 4 solution (TiO 2(0.2M H 2SO 4) nanotubes)>TiO 2 nanotubes >TiO 2 powder. This was attributed to the fact that TiO 2 nanotubes treated with H 2SO 4 was composed of smaller particles and had higher specific surface areas. Furthermore, the smaller TiO 2 particles were beneficial to the transfer and separation of photo-generated electrons and holes in the inner of and on the surface of TiO 2 particles and reduced the recombination of photo-generated electrons and holes. Acid treatment was particularly effective for TiO 2 nanotubes, this increase in activity was correlated with the concentration of H 2SO 4 solution.
文摘Silica sol ceramic mold was made at room temperature with JN-30 silica sol, silica powder and NH4Cl. It is found that the harden time of silica sol ceramic mold is only 0.5 to 1.5 h under the amount of NH4Cl solution of 7% to 8% with 15% concentration, and less surface cracks occur by using vacuum drying. The proper vacuum drying process parameters： vacuum drying temperature is 80 to 100℃, drying time is 5 h and vacuum is 0.06 to 0.07MPa. The harden mechanics, vacuum drying mechanics and the reason of less surface cracks of silica sol ceramic mold by vacuum drying： were also analyzed in this paper.
文摘The GC determination of aldehydes and ketones in stack gas was reported. The stack gas was collected with the dust sampler by isokinetic sampling technique, 2,4 dinitrophenylhydrazine in acidic solution was used to absorb aldehydes and ketones in stack gas specifically, to form their hydrazones, which were determined by GC with a capillary column of SE 54. The GC system can separate nine hydrazones of carbonyls interested with constant recovery rates of 94%—97%, giving lowest detectable limits of 0 05—1 0 ng. The standard gas of carbonyls were determined by this method with relative errors of -5% to -10%, percent coefficients of variation within 5%, and spiking recovery rates of 93%—97%. As an application of the method, the carbonyl pollutants were determined in stack gas samples of a chemical plant.
基金Funded by the Major State Basic Research Development Program of China(“973” Program)(No.2015CB655101)Natural Science Foundation of Hebei(No.E2016209283)+1 种基金National Natural Science Foundation of China(No.51402003)Open Foundation of Road Bridge and Structural Engineering Key Laboratory WHUT,China(No.DQZDJJ201504)
文摘By means of ^（29）Si and ^（27）Al magic angle spinning nuclear magnetic resonance（MAS NMR） combined with deconvolution technique, X-ray diffraction（XRD）, scanning electron microscopy（SEM） as well as energy dispersive X-ray system（EDX）, the effect of 5 wt% corrosive solutions（ viz. 5 wt% Na_2SO_4, MgSO_4, Na_2SO_^（4＋）Na Cl and Na_2SO_^（4＋）Na Cl＋Na_2CO_3） on C-S-H microstructure in portland cement containing 30 wt% fly ash was investigated.The results show that, in MgSO_4 solution, Mg2＋ promotes the decalcification of C-S-H by SO_4^（2-）,increasing silicate tetrahedra polymerization and mean chain length（MCL） of C-S-H. However, the substituting degree of Al^（3＋） for Si^（4＋）（Al[4]/Si） in the paste does not change evidently. Effect of Na_2SO_4 solution on C-S-H is not significantly influenced by Na Cl solution, while the MCL and Al[4]/Si of C-S-H in fly ashcement paste slightly change. However, the decalcification of C-S-H by SO_4^（2-） and CO_3^（2-） attack, as well as the activation of fly ash by SO_4^（2-） attack will increase the MCL and Al[4]/Si, which are both higher than that under Na_2SO_4 corrosion, MgSO_4 or Na_2SO_4 ＋Na Cl coordination corrosion.
基金Funded by the National Natural Science Foundation of China(No.12175107)the Natural Science Foundation of Nanjing University of Posts and Telecommunications(No.NY220030)
文摘The 2024 anodized aluminum alloy film was sealed by KAl(SO_(4))_(2)solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves,electrochemical impedance spectroscopy,and X-ray photoelectron spectroscopy.The experimental results show that the optimal parameters for KAl(SO_(4))_(2)sealing are 35℃,with the pH value of 8,the concentration of 8 g/L,and the sealing time of 3 min.The corrosion resistance of the KAl(SO_(4))_(2)sealed sample can be significantly improved than that of unsealed one,and is obviously superior to that of the conventional hydrothermal sealed sample.Furthermore,X-ray photoelectron spectroscopy demonstrates that more Al(OH)_(3)will be formed in the process of KAl(SO_(4))_(2)sealing,which will shrink the diameter of the microporous and therefore results in the excellent corrosion resistance.
基金financially supported by the Henan University of Science and Technology through a grant of Postgraduate Innovation Fund(No.CXJJ-Z015)the Foundation and Advanced Technology Fund of Henan Science and Technology Department(No.11230041002)the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT1234)
文摘The synthesis of Cu-doped ZnO nanosheets at room temperature was reported in our previous paper. The effects of annealing temperature on Cu-doped ZnO nanosheets were studied in this paper. Cu-doped ZnO nanosheets were annealed at 200-500℃ in air. The annealed specimens were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The results show that Cu concentration in Cu-doped ZnO nanosheets reduced with increasing annealing temperature. When annealing temperature was lower than Zn melting point （410℃）, the morphologies of the Cu-doped ZnO nanosheets remained nearly the same as that before annealing. However, when the annealing temperature was over Zn melting point, Cu-doped ZnO nanosheets changed to nanowires, wormlike nanosheets or did not change. The change of Cu concentration in Cu-doped ZnO nanosheets is explained by oxidation thermodynamics. A physical model is suggested to explain the morphology changes of Cu-doped ZnO nanosheets, based on the existence of Cu-rich layer beneath Cu-doped ZnO nanosheets.
文摘A regenerative absorption process for removal of SOx from FCC off-gas using LAS/ H2SO4 solution as absorbant was studied and pilot-plant experiments were carried out. A mass transfer- reaction model for the SO2 absorption process was established based on pilot-plant experiments, and the concentration distribution of components in the liquid film, and the partial pressure and mass transfer rate of SO2 along the height of the absorption tower, was calculated from this model. The numerical simulation results were compared with the experimental results and proved that the model can be used for describing the SO2 absorption process.
基金supported by NSFC (10401011,10871153)China Postdoctoral Science Foundation (2005037660)
文摘Under the framework of white noise analysis, the existence of scattering solutions to the abstract dynamical φ4^4 wave equations in terms of generalized operators （see Section 3 below） is proven via a combination of the characterization for the symbol of generalized operators and the classical scattering results. In addition, some properties （Poincare invariance and irreducibility） of the solutions are discussed.
文摘Time-resolved IR absorption spectroscopy has been used to atudy the photochemistry of W(CO)_6 in cyclohexane, carbon tetrachloride, and the mixture of carbon tetrachloride and cyelohexane. The reastion of photolytically generated W(CO)_5. C_6H_(12) with CCl_4 was investigated. An intermediate with a lifetime of about 0.5ms, presumably attributed as W(GO)_5.CCl_4, was first observed.
基金the National Natural Science Foundation of China (21376282,21676035,21878029)Chongqing Science and Technology Commission (cstc2018jcyjAX0668)+2 种基金Shandong Province Natural Science Foundation (ZR2020QB18)China Postdoctoral Science Foundation (22012 T50762&2011 M501388)Graduate Student Research Innovation Project,Chongqing University (CYB18046)。
文摘In this study,the benign target double terpyridine parts based amphiphilic ionic molecules(AIMs 1,2)and the reference single terpyridine segment included AIMs(AIMs 3,4)were synthesized through a multi-step method,and the molecular structures were fully characterized.The excellent anticorrosion of the target AIMs for copper surface in H_(2)SO_(4) solution was demonstrated by the electrochemistry analysis,which was more superior over those of the reference AIMs.The standard adsorption free energy changes of the target AIMs calculated by the adsorption isotherms were lower than -40 kJ·mol^(-1),suggesting an intensified chemical adsorption on metal surface.The molecular modeling and molecular dynamic computation of the studied AIMs were performed,demonstrating that the target AIMs exhibited lower highest occupied molecular orbital-lowest unoccupied molecular orbital energy gaps and greater adsorption energies than the reference ones.The chemical adsorption of the AIMs on metal surface was revealed by various spectroscopic methods including scanning electron microscopy,atomic force microscopy,Fourier transform infrared spectroscopy,attenuated total reflection infrared spectroscopy,Raman and X-ray diffraction.
文摘The cyclic plastic straining electrode technique has been used to investigate the transient electrochemical behaviour of Fe-26Cr1Mo stainless steel in 1M H2SO4 solution at a passive potential.The influence of plastic strain amplitude and plastic strain rate on the dissolution current response was analysed. The experimental results showed that the transient current was dependent on the competitive process of the surface film rupture and repassivation of the new surface. The high plastic strain amplitude and the high plastic strain rate caused a change of electrochemical activity of specimen surface. In the condition of low strain amplitude and strain rate, the characteristics of current response was mainly relative tp the process of new surface repassivation.The competition kinetics has been analysed through the comparison of plastic strain rate and repassivating rate
基金Project supported by the CNPC Application Fundamentals Research Project,“Basic Research on Safe Operation of In-Service High-Strength Pipelines”(Grant No.2014B-3313).
文摘Oil and gas line pipes are laid underground and run through different areas in the laying process,so they will be subjected to different degrees of corrosion and even crack,leading to enormous casualties and economic losses.In order to guarantee the safe operation of line pipes,therefore,it is significant to investigate the electrochemical corrosion behaviors of pipe steel in a simulated soil environment.In this paper,the electrochemical corrosion behaviors of the base metals and welding materials of API 5L X90 steel longitudinally submerged arc welding pipes in near-neutral simulated soil solution(NS4)were studied by means of the electrochemical impedance spectroscopy(EIS)and the potentiodynamic polarization testing technology.It is shown that the typical characteristic of anodic dissolution is presented but with no passivation phenomenon when X90 linepipe steel is put in NS4 solution.The base material is thermodynamically more stable than the seam weld material.The base material and seam weld samples were polarized under -850 mV polarization potential for different durations.It is demonstrated that with the proceeding of polarization,the polarization resistance and the corrosion resistance increase while the corrosion current density decreases.And the corrosion resistance of base material is better than that of seam weld material.
基金supported in part by a Sloan fellowship and an NSERC grant for Chenby a grant from NSF of China for Li.by a grant from NSF of USA for Tian
文摘A surface E is a graph in R^4 if there is a unit constant 2-form ω on R^4 such that <e_1∧e_2.ω>≥v_0>0 where{e_1.e_2}is an orthonormal frame on Σ.We prove that.if v_0≥on the initial snrface,then the mean curvature flow has a global solution and the scaled surfaces converge to a self-similar solution.A surface Σ is a graph in M_1×M_2 where M_1 and M_2 are Riemann surfaces. if<e_1∧e_2.ω>≥v_0>0 where w_1 is a Khler form on M_1.We prove that.if M is a Khler-Einstein surface with scalar curvature R.v_0≥ on the initial surface,then the mean curvature flow has a global solution and it sub-converges to a minimal surface,if.in addition.R≥0 it converges to a totally geodesic surface which is holomorphic.
